MuSCAT2: four-color simultaneous camera for the 1.52-m Telescopio Carlos Sánchez

Narita, Norio; Fukui, A.; Kusakabe, Nobuhiko; Watanabe, Noriharu; Πάλλη, Ε.; Parviainen, H.; Montañés-Rodŕıguez, P.; Murgas, F.; Monelli, M.; Aguiar, M.; Prieto, Jorge A. Pérez; Oscoz, A.; Leon, Jerome de; Mori, M.; Tamura, Motohide; Yamamuro, Tomoyasu; Béjar, V. J. S.; Crouzet, Nicolas; Hidalgo, D.; Klagyivik, P.; Luque, R.; Nishiumi, Taku

doi:10.1117/1.jatis.5.1.015001

Cited by 63 publications

(54 citation statements)

References 40 publications

(39 reference statements)

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“…We observed two full and one partial transits of TOI 263.01 with the MuSCAT2 multicolour imager (Narita et al 2019) installed in Telescopio Carlos Sanchez (TCS) in the Teide Observatory on the nights of 18.12.2018, 19.12.2018, and 02.01.2019. MuS-CAT2 is a four-colour instrument consisting of four independently controlled CCDs, but one of the CCDs was under maintenance, and the observations were carried out simultaneously in three colours (r , i , z s ).…”

Section: Muscat2 Photometrymentioning

confidence: 99%

“…Our analysis is based on three nights of simultaneous ground-based multicolour transit photometry in r , i , and z s bands taken with MuSCAT2 multicolour imager (Narita et al 2019) installed in the 1.5 m Telescopio Carlos Sanchez (TCS) in the Teide Observatory, three transit light curves observed in g , r , and i bands with the SINISTRO cameras in the 1 m LCOGT telescopes, and a TESS light curve from Sector 3. The analysis uses a light contamination model included in PyTransit v2, and yields the posterior densities for the model parameters defining the candidate's geometry and orbit, as well as an estimate of the true radius ratio in the presence of possible light contamination from blended sources, or from the transiting object itself.…”

Section: Introductionmentioning

confidence: 99%

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MuSCAT2 multicolour validation of TESS candidates: an ultra-short-period substellar object around an M dwarf

Parviainen

Πάλλη

Osorio

et al. 2020

A&A

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Context. We report the discovery of TOI 263.01 (TIC 120916706), a transiting substellar object (R = 0.87 R Jup ) orbiting a faint M3.5 V dwarf (V = 18.97) on a 0.56 d orbit.Aims. We set out to determine the nature of the TESS planet candidate TOI 263.01 using ground-based multicolour transit photometry. The host star is faint, which makes RV confirmation challenging, but the large transit depth makes the candidate suitable for validation through multicolour photometry.Methods. Our analysis combines three transits observed simultaneously in r , i , and z s bands using the MuSCAT2 multicolour imager, three LCOGT-observed transit light curves in g , r , and i bands, a TESS light curve from Sector 3, and a low-resolution spectrum for stellar characterisation observed with the ALFOSC spectrograph. We model the light curves with PyTransit using a transit model that includes a physics-based light contamination component that allows us to estimate the contamination from unresolved sources from the multicolour photometry. This allows us to derive the true planet-star radius ratio marginalised over the contamination allowed by the photometry, and, combined with the stellar radius, gives us a reliable estimate of the object's absolute radius. Results. The ground-based photometry strongly excludes contamination from unresolved sources with a significant colour difference to TOI 263. Further, contamination from sources of same stellar type as the host is constrained to levels where the true radius ratio posterior has a median of 0.217 and a 99 percentile of 0.286. The median and maximum radius ratios correspond to absolute planet radii of 0.87 and 1.41 R Jup , respectively, which confirms the substellar nature of the planet candidate. The object is either a giant planet or a brown dwarf (BD) located deep inside the socalled "brown dwarf desert". Both possibilities offer a challenge to current planet/BD formation models and makes TOI 263.01 an object deserving of in-depth follow-up studies.

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Section: Muscat2 Photometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

MuSCAT2 multicolour validation of TESS candidates: an ultra-short-period substellar object around an M dwarf

Parviainen

Πάλλη

Osorio

et al. 2020

A&A

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“…We observed three transits of K2-100 with the MuSCAT2 multicolour photometer (Narita et al 2019) installed in the Carlos Sanchez Telescope (TCS) in the Teide observatory on the nights of 2018-12-28 UTC, 2019-01-02 UTC, and 2019-01-22 UTC. All observations covered from 2 to 3.2 hours around the expected midtransit time, and were carried simultaneously in the r , i , and z passbands with a common exposure time of 10 seconds.…”

Section: Photometrymentioning

confidence: 99%

Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Barragán

Aigrain

Kubyshkina

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of HARPS-N radial velocity observations of K2-100, a young and active star in the Praesepe cluster, which hosts a transiting planet with a period of 1.7 days. We model the activity-induced radial velocity variations of the host star with a multi-dimensional Gaussian Process framework and detect a planetary signal of 10.6 ± 3.0 m s −1 which matches the transit ephemeris, and translates to a planet mass of 21.8 ± 6.2 M ⊕ . We perform a suite of validation tests to confirm that our detected signal is genuine. This is the first mass measurement for a transiting planet in a young open cluster. The relatively low density of the planet, 2.04 +0.66 −0.61 g cm −3 , implies that K2-100b retains a significant volatile envelope. We estimate that the planet is losing its atmosphere at a rate of 10 11 − 10 12 g s −1 due to the high level of radiation it receives from its host star.

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“…is, MuSCAT2 multicolour imager installed in the 1.5 m Telescopio Carlos Sanchez in the Teide Observatory (Narita et al 2018). The noise level, 1000 ppm over an exposure of 60 s, is also based on existing observations for a V = 12 star with this setup.…”

Section: Methodsmentioning

confidence: 99%

“…We use transit observations of WASP-43b and WASP-12b to study the contamination estimation in practice. The observations were carried out with MuSCAT2, a new four-colour imager in-stalled in the 1.5 m Carlos Sanchez Telescope (TCS) in the Teide Observatory (OT), Tenerife (Narita et al 2018). The instrument has the capability of simultaneous imaging in g (400-550 nm), r (550-700 nm), i (700-820 nm), and z s (820-920 nm) bands, which closely match our simulations.…”

Section: Muscat2 Observationsmentioning

confidence: 99%

Multicolour photometry for exoplanet candidate validation

Parviainen

Tingley²,

Deeg

et al. 2019

A&A

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Context. The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate validation will require a significant amount of follow-up resources. Radial velocity (RV) follow-up can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate's true nature needs to be determined based on these alternative methods alone. Aims. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source (transiting planet, eclipsing binary, etc.), and not from an instrumental artefact. Particularly, we aim to answer how securely can we estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model in a Bayesian parameter estimation setting. More generally, we study how the contamination level, colour differences between the planet host and contaminant stars, transit signal-to-noise ratio, and available prior information affect the contamination and true radius ratio estimates. Methods. The study is based on simulations and ground-based multicolour transit observations. The contamination analyses are carried out with a contamination model integrated into the PyTransit v2 transit modelling package, and the observations are carried out with the MuSCAT2 multicolour imager installed in the 1.5 m Telescopio Carlos Sanchez in the Teide Observatory, Tenerife. Results. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.

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MuSCAT2: four-color simultaneous camera for the 1.52-m Telescopio Carlos Sánchez

Cited by 63 publications

References 40 publications

MuSCAT2 multicolour validation of TESS candidates: an ultra-short-period substellar object around an M dwarf

MuSCAT2 multicolour validation of TESS candidates: an ultra-short-period substellar object around an M dwarf

Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Multicolour photometry for exoplanet candidate validation

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